The headrests are not "active" in an e90 sedan, just go hold the adjuster clip and pull them out. The active head restrains/curtains are in the sills of the cars a and b pillars. The headrests you are thinking of are in the convertible or e93 as we call it as they don't have b pillars.

2009 model year and up E9x most certainly do have active head restraints. They will move up and forward in a rear end collision to prevent whiplash.